Height-adjustable beds are known in the art, and are commonly used in hospitals and other medical institutions. A frame member of the bed, that supports e.g. a mattress for a patient to lie on, is adjustable in an upward and downward direction. The frame member may be adjustable independently at its head and foot end, in order that the angle of incline of the mattress can be adjusted.
Height-adjustable beds have numerous advantages. For example, the mattress of a height-adjustable bed can be lowered to a position close to the ground. A low mattress position is particularly advantageous for elderly or mentally disabled patients, who are prone to falling out of the bed accidentally or intentionally. The lower the position of the mattress, the less likely it is that a falling patient will be hurt. Furthermore, it is harder for a patient to alight from a mattress positioned close to the ground. However, it is advantageous that the mattress can be raised so that a patient lying on the mattress is at a suitable height for care workers to attend to.
It is desirable that patient care access is provided at the head and/or foot ends of the bed when the mattress is adjusted to any height.
In known height-adjustable beds, the height-adjustable frame member is held at the head and foot end of the bed by respective supports. These supports are often cumbersome, or insufficiently strong to provide a stable platform that will meet the European regulations for hospital bed frames, and comprise powered drive means for raising and lowering the respective ends of the height-adjustable frame member. The supports limit or prevent patient care access from the head and foot ends of the bed. This is a particular problem when certain medical procedures must be carried out on a patient, such as cardiopulmonary resuscitation (CPR). CPR is usually carried out from the head end of a bed, since access to the patient's head is required.
Known height-adjustable beds generally comprise a height-adjustable upper frame member and a fixed lower frame member, the upper frame member being for supporting the mattress and the lower frame member providing rigidity to the bed when the upper frame member is at a raised position. WO01/45626 shows a height-adjustable bed without a lower frame member.
WO03/070145 discloses a height-adjustable bed having both a height adjustable upper frame member and a height-adjustable lower frame member.
However, safety problems arise with beds having height-adjustable frame members. Most notably, it is possible for a person to trap a limb between the height-adjustable parts, e.g. between the upper frame member and the fixed lower frame member during lowering of the upper frame member. WO03/088885 describes obstacle detection devices in such a bed in the form of a wireless curtain, e.g. formed by light beams, or a force-sensing switch.